Serum levels of reduced glutathione, oxidized glutathione, and glutathione reductase activity in minor recurrent aphthous stomatitis patients.

Background/purpose: Recurrent aphthous stomatitis (RAS) is one of the most prevalent oral mucosa diseases with unknown etiology. Reduced glutathione (GSH) is a major intracellular non-protein physiological antioxidant, and it has been demonstrated that GSH deficiency may be related to cardiovascular, immune, and diabetes. The purpose of this investigation was to evaluate the potential roles of GSH, oxidized glutathione (GSSG), and glutathione reductase (GR) in the etiopathogenesis of minor recurrent aphthous stomatitis (MiRAS). Materials and methods: The study comprised 87 patients with idiopathic MiRAS and 90 race-, age-, and gender-matched healthy individuals. The spectrophotometric method was used to determine serum GSH and GSSG concentrations as well as GR activity. The GSSG/GSH ratios were subsequently computed. For statistical evaluation, the independent sample t test, Pearson's chi-square test, Mann-Whitney U test, Kruskal-Wallis H test, and Binary logistic regression analysis were used. Results: The serum GSSG level, GR activity and GSSG/GSH ratio were statistically higher in MiRAS patients, whereas the concentration of serum GSH was significantly decreased. With the exception of GR, serum GSSG, GSH, and GSSG/GSH were all significantly associated with MiRAS. Serum GSSG can be regarded as a risk factor, whereas serum GSH and GSSG/GSH maybe considered as protective factors against the occurrence of MiRAS. Conclusion: GSSG may be a potential danger factor to MiRAS and GSH may be a protective factor, while GR may not play an important role in the aetiopathogenesis of MiRAS.

Optimized Reversed-Phase Liquid Chromatography/Mass Spectrometry Methods for Intact Protein Analysis and Peptide Mapping of Adeno-Associated Virus Proteins.

Recombinant adeno-associated viruses (AAVs) have emerged as the leading gene delivery platform owing to their nonpathogenic nature and long-term gene expression capability. The AAV capsid, in addition to protecting the viral genome, plays an important role in viral infectivity and gene transduction, indicating the value of the constituent viral proteins (VPs) being well-characterized as part of gene therapy development. However, the limited sample availability and sequence homology shared by the VPs pose challenges to adapt existing analytical methods developed for conventional biologics. In this study, we report the development of reversed-phase liquid chromatography/mass spectrometry-based methods for characterization of AAV capsid proteins at intact protein and peptide level with reduced sample consumptions. The developed methods allowed the measurement of VP expression with fluorescence detection and intact mass/post-translational modifications (PTMs) analysis through a benchtop time-of-flight mass spectrometer. The general applicability and validity of the methods for gene therapy product development were demonstrated by applying the optimized methods to multiple common AAV serotypes. A 1-h enzymatic digestion method was also developed using 1.25 µg of AAV VPs, providing >98% protein sequence coverage and reproducible relative quantification of various PTMs of the VPs. The efficient and sensitive analyses of AAV capsid proteins enabled by the reported methods provide further understanding and offer guidance in the development and manufacturing of AAV-related therapeutics.

Capillary Electrophoresis-Sodium Dodecyl Sulfate with Laser-Induced Fluorescence Detection as a Highly Sensitive and Quality Control-Friendly Method for Monitoring Adeno-Associated Virus Capsid Protein Purity.

The capsid protein purity of adeno-associated virus (AAV) is considered a critical quality attribute of AAV-based gene therapy products. However, the analytical methods currently available to monitor the viral capsid proteins, which are present in extremely low concentrations, have limited sensitivity and robustness, thus limiting their general applicability. As a result, there is an urgent need to develop robust separation methods with highly sensitive detection. In this article, we describe the first denaturation and fluorescence labeling procedure for AAV capsid proteins using the pyrylium dye Chromeo™ P503, enabling the establishment of the first capillary electrophoresis-sodium dodecyl sulfate (CE-SDS) method combined with laser-induced fluorescence (LIF) detection for AAV. Upon optimization using a quality-by-design approach, the newly developed method features a simple and robust one-step sample preparation workflow resulting in consistently labeled and denatured viral protein samples, which can subsequently be separated and quantified by CE-LIF. The method has been validated to be accurate and precise with a linear range of 50-150% of the nominal concentration of 2.0 × 1011 vector genomes per mL (vg/mL). The detection limit and quantitation limit were established to be 8.0 × 107 vg/mL (∼0.8 ng/mL) and 4.2 × 108 vg/mL (∼4 ng/mL), respectively, representing the highest sensitivity achieved for AAV capsid protein quantitation reported to date and a linear dynamic range of 8.0 × 107-3.0 × 1011 vg/mL. A comparison of the CE-SDS LIF method with existing methods, such as CE-SDS ultraviolet and sodium dodecyl sulfate-polyacrylamide gel electrophoresis with SYPRO Ruby stain, indicated that the new method has superior resolution and a significant increase in signal intensity. Capsid protein purity analysis of multiple AAV serotypes, including AAV5, scAAVrh10, AAV2, and AAV6, has been demonstrated for the first time using the same method, indicating the newly developed AAV labeling procedure and CE-LIF analysis could serve as a Quality Control-friendly platform and best-in-class analytical method for the control of AAV capsid protein purity.

Galectin-3 and acute heart failure: genetic polymorphisms, plasma level, myocardial fibrosis and 1-year outcomes.

Aim: This study sought to investigate the relationship between galectin-3 (Gal-3), myocardial fibrosis (MF) and outcomes in acute heart failure. Materials & methods: The single-nucleotide polymorphisms (SNPs) of LGALS3 at rs4644 and rs4652, plasma Gal-3 level, MF and major adverse events (MAEs) were obtained. Results: There was no significant difference in MAEs when categorizing patients by the LGALS3 SNPs at rs4644 and rs4652. The circulating Gal-3 was related to the degree of MF (p < 0.001). Plasma Gal-3 level and MF can predict an increased risk of MAEs (p < 0.001, p = 0.023, respectively). Conclusion: Not the SNPs of LGALS3 but Gal-3 and MF can predict MAEs in acute heart failure at 1 year of follow-up.

Serum levels of total antioxidant status, nitric oxide and nitric oxide synthase in minor recurrent aphthous stomatitis patients.

BACKGROUND: Recurrent aphthous stomatitis (RAS) is one of the most common inflammatory ulcerative conditions of oral cavity with uncertain etiology. Several studies have reported that oxidative stress may be associated with RAS. The aim of this study was to compare the serum levels of total antioxidant status (TAS), nitric oxide (NO) and nitric oxide synthase (NOS) in minor RAS (MiRAS) patients with healthy individuals and determine the possible association of MiRAS with the 3 physiological parameters mentioned above. METHODS: Ninety patients with idiopathic MiRAS and 90 race-, age- and sex-matched healthy individuals were included in this study. All these subjects were allocated to 3 groups: MiRAS patients in the active stage (Group A); the same MiRAS patients in Group A in the inactive stage (Group B); healthy individuals without MiRAS (Group C). Serum levels of TAS, NO and NOS were determined by the spectrophotometric method. Independent sample t test and paired t test were performed for statistical evaluation. RESULTS: Serum TAS level of Group A was significantly decreased than that of Group C, whereas the serum level of NO was significantly higher in Group A as compared to Group C (P < .05). The serum levels of TAS and NO in Group B were no significant differences when compared with those in Group A or Group C. No significant differences in NOS activities were also found between the 3 groups (P > .05). CONCLUSIONS: MiRAS is associated with decreased TAS and increased NO levels, but NOS may not play an important role in the aetiopathogenesis.

Chronic heart failure in patients with nonalcoholic fatty liver disease: prevalence, clinical features, and relevance.

Objective This study was performed to assess the prevalence of nonalcoholic fatty liver (NAFL) in patients with symptomatic congestive heart failure (CHF) and compare the clinical features with those of patients without NAFL. Methods In total, 102 patients with CHF were divided into NAFL and non-NAFL groups according to their hepatic ultrasonography findings. All patients underwent transthoracic echocardiography and cardiac magnetic resonance examination. Follow-up was performed for major cardiovascular events (MACE) and readmission due to heart failure at 1, 3, 6, and 12 months after the index hospitalization. Results NAFL was detected in 37 of 102 patients (36.27%). Compared with the non-NAFL group, patients with NAFL were younger, had a higher body mass index and left ventricular (LV) mass index, and had more severe fibrosis. MACE and readmission occurred in 15 patients in the NAFL group and 29 patients in the non-NAFL group, without a significant difference. Linear regression analysis revealed that after adjusting for confounders, NAFL was independently associated with the LV fibrosis size and the ratio of the LV fibrosis size to the LV mass index. Conclusions NAFL is present in more than one-third of patients with CHF and is associated with the severity of LV fibrosis.

Enzymatic antioxidants status in patients with recurrent aphthous stomatitis.

BACKGROUND: Oxidative stress (OS) has been thought to play a main role in the etiopathogenesis of recurrent aphthous stomatitis (RAS), which is one of the most common oral mucosal diseases characterized by recurrent and painful oral ulcers. The aim of this investigation was to evaluate the enzymatic antioxidants status in patients with RAS in the active stage and remission stage. METHODS: Ninety-seven patients with idiopathic minor RAS and 102 race-, age- and gender-matched healthy individuals were recruited. All these subjects were allocated to three groups: RAS patients with active lesion (group A); the same patients in group A in the remission stage of RAS (group B); and healthy individuals without RAS (group C). Following an overnight fast, blood samples were obtained. The serum levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSHPx) were measured by the spectrophotometric method. Independent-samples t-test and paired t-test were performed for statistical evaluation. RESULTS: The serum levels of SOD, GSHPx, and CAT (83.9 ± 17.1 U/ml, 6687.2 ± 2629.2 U/ml, 1789.7 ± 593.8 U/l) were found to be significantly lower in group A as compared to those of group B (99.8 ± 11.1 U/ml, 9364.1 ± 1607.9 U/ml, 2789.1 ± 1113.4 U/l; P < 0.05) or group C (97.3 ± 12.1 U/ml, 9246.2 ± 2376.1 U/ml, 2819.0 ± 914.8 U/l; P < 0.05). No significant differences were found between group B and group C with respect to any one of these enzymatic antioxidants (P > 0.05). CONCLUSIONS: Our results indicate that enzymatic antioxidant defense system is impaired in RAS patients with active lesion and seems to play a crucial role in its pathogenesis.

The normal range of maximum mouth opening and its correlation with height or weight in the young adult Chinese population.

BACKGROUND/PURPOSE: Maximum mouth opening (MMO) is an important diagnostic reference for dental clinicians. However, the relationship between either body height or weight of the individual and their subsequent MMO has, up to now, been unclear. The purpose of this study was to measure the MMO of healthy young Chinese adults and to analyze the possible correlation of MMO with either height or weight. MATERIALS AND METHODS: A total of 452 young Chinese adults, aged 20-35 years (238 males, 214 females) were selected for this cross-sectional study. We recorded the MMO, age, sex, height, and weight of the participants. Two standardized examiners performed the clinical oral assessments. Independent sample t tests were used to examine the difference in MMO relative to sex. Pearson's correlation and simple linear regression were used to estimate the correlation between MMO and either height or weight. RESULTS: The average MMO across the 452 participants was 52.02 ± 5.09 mm, and the average MMO of males (54.18 ± 5.21 mm) was significantly larger than that of females (49.62 ± 3.69 mm; P < 0.001). The mean MMO was moderately positively correlated with height (r = 0.54; P < 0.001) and weight (r = 0.50; P < 0.001). In the regression model, it was estimated that, for every 10 cm or 10 kg, MMO increased by about 3.6 mm or 1.8 mm, respectively. CONCLUSION: With the limits of the present study, both height and weight were found to be significantly correlated with the MMO of Chinese young adults and may be significant predictors of MMO measurement.

Effect of plasma nitriding and titanium nitride coating on the corrosion resistance of titanium.

STATEMENT OF PROBLEM: The passive film on the surface of titanium can be destroyed by immersion in a fluoridated acidic medium. Coating with titanium nitride (TiN) may improve the corrosion resistance of titanium. PURPOSE: The purpose of this in vitro study was to investigate the effect of duplex treatment with plasma nitriding and TiN coating on the corrosion resistance of cast titanium. MATERIAL AND METHODS: Cast titanium was treated with plasma nitriding and TiN coating. The corrosion resistance of the duplex-treated titanium in fluoride-containing artificial saliva was then investigated through electrochemical and immersion tests. The corroded surface was characterized by scanning electron microscopy (SEM) with energy-dispersive spectroscopy surface scan analysis. The data were analyzed using ANOVA (α=.05) RESULTS: Duplex treatment generated a dense and uniform TiN film with a thickness of 4.5 µm. Compared with untreated titanium, the duplex-treated titanium displayed higher corrosion potential (Ecorr) values (P<.001) and lower corrosion current density (Icorr) values (P<.001). SEM results showed that the surface of untreated titanium was more heavily corroded than that of duplex-treated titanium. Surface scan analysis of duplex-treated titanium that had been immersed in artificial saliva containing 2 g/L fluoride revealed fluorine on the titanium surface, whereas fluorine was not observed on the surface of untreated titanium after immersion in fluoride-containing artificial saliva. The concentration of titanium ions released from the treated titanium was less than the amount released from untreated titanium (P<.001). CONCLUSIONS: Duplex treatment by plasma nitriding and TiN coating significantly improved the corrosion resistance of cast titanium in a fluoride-containing environment.

SpeB proteolysis with imaged capillary isoelectric focusing for the characterization of domain-specific charge heterogeneities of reference and biosimilar Rituximab.

The charge variations of therapeutic monoclonal antibody reveal important information of the post-translational modifications that may potentially impact the potency and safety of pharmaceutical products, especially during the evaluation of biosimilarity of therapeutic proteins. In this work, a novel SpeB-based proteolysis strategy coupling with imaged capillary isoelectric focusing was developed for the determination of domain-specific charge heterogeneities of innovator and generic Rituximab drug products from United States, European and Indian markets. It was observed that innovator Rituximab from the United States and Europe share highly similar peak distributions and charge heterogeneities with 26.2-26.6% Fc/2, 28.9-29.3% LC and 44.4-44.5% Fd peak areas detected, respectively, while multiple basic variations of Fc/2 and less acidic LC and Fd species were found from generic Rituximab from India with 20.9% Fc/2, 32.3% LC and 46.9% Fd peak areas detected. It was also demonstrated that structural changes caused by Carboxypeptidase B treatment and deamidation study at pH extremes could be sensitively captured with the established method, with the results further indicating that the generic product's basic variations of Fc/2 were un-cleaved Lysine residues, while the lack of certain acidic peaks on LC and Fd probably was due to the lower level of deamidation. This new strategy could become a useful tool to reveal domain-specific charge heterogeneities profiles of a variety of therapeutic monoclonal antibodies in regulated environments.

Assessment of serum malondialdehyde, uric acid, and vitamins C and E levels in patients with recurrent aphthous stomatitis.

BACKGROUND/PURPOSE: Recurrent aphthous stomatitis (RAS) is a common oral mucosal disease. Recently, oxidative stress has been thought to play a major role in the etiopathogenesis of RAS. The aim of this investigation was to compare the serum levels of an important oxidant agent [malondialdehyde (MDA)] and nonenzymatic antioxidants [uric acid (UA) and vitamins C and E] in patients with RAS versus healthy individuals. MATERIALS AND METHODS: Ninety-seven patients with idiopathic minor RAS and 97 race-, age-, and sex-matched healthy individuals were included in this study. All these individuals were allocated to three groups: RAS patients in the active stage (Group A); the same RAS patients in Group A in the remission stage (Group B); and healthy individuals without RAS (Group C). The serum levels of MDA, UA, and vitamins C and E were measured by the spectrophotometric method. Independent sample t test and paired t test were performed for statistical evaluation. RESULTS: Serum MDA level of Group A was significantly higher than that of Group B (P = 0.040) or Group C (P = 0.011), whereas the serum level of vitamin E was significantly decreased in Group A as compared with Group B (P = 0.012) or Group C (P = 0.001). No statistically significant differences were found between Group B and Group C in terms of MDA, UA, and vitamins C and E serum levels (P > 0.05). CONCLUSION: With the double-faced character of oxidant/antioxidant, UA and vitamin C may not play a crucial role in the pathogenesis of RAS. However, MDA and vitamin E can be used as indicators for RAS.

[Effect of TiO2-SiO2-SnOx film with different firing temperatures on bond strength of low-fusing dental porcelain to pure titanium].

OBJECTIVE: To evaluate the influence of TiO(2)-SiO(2)-SnOx nano-coatings with different firing temperatures on the bond strength of low-fusing dental porcelain to pure titanium. METHODS: The surface of pure titanium was coated uniformly with TiO(2)-SiO(2)-SnOx nano-coatings by solution-gelatin (Sol-Gel) technology and then fired at 300 °C (group A) or 750 °C (group B) for 1 h. The specimens without any coatings were the control group (group C). There were 10 specimens in each group. Dental porcelain was sintered on the surface of titanium specimens. Surface roughness and contact angle of the coatings were also detected. The titanium-porcelain bond strength was investigated according to YY 0621-2008 standards using three-point flexure bond test. The phase composition of the TiO(2)-SiO(2)-SnOx nano-coatings was characterized by X-ray diffraction(XRD). The interface of titanium-porcelain and TiO(2)-SiO(2)-SnOx nano-coatings were observed using scanning electron microscope (SEM). RESULTS: No rutile phase was found in these specimens of group A and group B. The surface roughness of group A, B, C was (0.97 ± 0.06), (0.99 ± 0.03), (0.96 ± 0.07) µm, respectively. No significant difference was found among the three groups. Compared with that of group C (64.37° ± 3.01°), contact angles detected in group A (52.04° ± 3.15°) and group B (85.27° ± 4.17°) were significantly different (P < 0.05). The bond strength of titanium-porcelain in group A [(35.66 ± 2.65) MPa] was significantly increased compared with those in group B [(26.18 ± 2.22) MPa] and group C [(31.66 ± 3.52) MPa]. SEM photomicrographs of titanium-porcelain interface morphology of the specimens before porcelain sintering showed that TiO(2)-SiO(2)-SnOx nano-coatings in group A were compact and homogeneous with petty cracks and those in group B was loose and arranged disorderly. CONCLUSIONS: TiO(2)-SiO(2)-SnOx nano-coating fired at 300 °C is significantly effective in improving the titanium-porcelain bond strength.

Defining the Neuropeptidome of the Spiny Lobster Panulirus interruptus Brain Using a Multidimensional Mass Spectrometry-Based Platform.

Decapod crustaceans are important animal models for neurobiologists due to their relatively simple nervous systems with well-defined neural circuits and extensive neuromodulation by a diverse set of signaling peptides. However, biochemical characterization of these endogenous neuropeptides is often challenging due to limited sequence information about these neuropeptide genes and the encoded preprohormones. By taking advantage of sequence homology in neuropeptides observed in related species using a home-built crustacean neuropeptide database, we developed a semi-automated sequencing strategy to characterize the neuropeptidome of Panulirus interruptus, an important aquaculture species, with few known neuropeptide preprohormone sequences. Our streamlined process searched the high mass accuracy and high-resolution data acquired on a LTQ-Orbitrap with a flexible algorithm in ProSight that allows for sequence discrepancy from reported sequences in our database, resulting in the detection of 32 neuropeptides, including 19 novel ones. We further improved the overall coverage to 51 neuropeptides with our multidimensional platform that employed multiple analytical techniques including dimethylation-assisted fragmentation, de novo sequencing using nanoliquid chromatography-electrospray ionization-quadrupole-time-of-flight (nanoLC-ESI-Q-TOF), direct tissue analysis, and mass spectrometry imaging on matrix-assisted laser desorption/ionization (MALDI)-TOF/TOF. The high discovery rate from this unsequenced model organism demonstrated the utility of our neuropeptide discovery pipeline and highlighted the advantage of utilizing multiple sequencing strategies. Collectively, our study expands the catalog of crustacean neuropeptides and more importantly presents an approach that can be adapted to exploring neuropeptidome from species that possess limited sequence information.

A one-step preparation method of monolithic enzyme reactor for highly efficient sample preparation coupled to mass spectrometry-based proteomics studies.

Mass spectrometry (MS) coupled to sample preparation and separation techniques has become a primary tool for proteomics studies. However, due to sample complexity, it is often challenging to achieve fast and efficient sample preparation prior to MS analysis. In recent decades, monolithic materials have been developed not only as chromatographic media, but also as efficient solid supports for immobilizing multiple types of affinity reagents. Herein, the N-acryloxysuccinimide-co-acrylamide-co-N,N'-methylenebisacrylamide (NAS-AAm-Bis) monolith was fabricated within silanized 200 µm i.d. fused-silica capillaries and was used as an immobilized enzyme reactor (IMER). The column was conjugated with trypsin/Lys-C and Lys-N enzymes to allow enzymatic digestions to occur while protein mixture was loaded onto the IMER column followed by MS-based proteomics analysis. Similar MS signal and protein sequence coverage were observed using protein standard bovine serum albumin (BSA) compared to in-solution digestion. Furthermore, mouse serum, yeast, and human cell lysate samples were also subjected to enzymatic digestion by both IMER (in seconds to minutes) and conventional in solution digestion (overnight) for comparison in large-scale proteomics studies. Comparable protein identification results obtained by the two methods highlighted the potential of employing NAS-based IMER column for fast and highly efficient sample preparation for MS analysis in proteomics studies.

[Porewater Dissolved Methane in Cyperus malaccensis Marshes Along Salinity Gradient in the Minjiang River Estuary].

Physicochemical properties of soil and dissolved methane concentrations of porewater in the sediments of the Cyperus malaccensis marshes along a salinity gradient in the Minjiang River estuary were evaluated, and the spatial-temporal characteristics and main impact factors were discussed. The average concentrations of dissolved methane in porewater were 331.18, 299.94 and 638.58 µmol x L(-1), respectively in the Shanyutan, Bianfuzhou and Xiayangzhou wetlands in summer. In the winter, they were 9.04, 266.67 and 322.68 µmol x L(-1), respectively. The dissolved methane concentration in porewater was higher in summer than those in winter (P < 0.05). Overall, the concentrations of dissolved methane in porewatdr showed an increasing trend from brackish to freshwater marshes. Multivariate statistics analysis showed that the concentrations of dissolved methane in porewater was positively correlated with soils temperature and DOC (P < 0.05), but negatively correlated with soils pH, salinity, and the concentrations of porewater SO4(2-) and Cl-. Spatial-temporal distribution of porewater dissolved methane in estuarine marshes represents a final result of multiple factors, including soil physicochemical properties and hydrodynamic condition.

Recent advances in coupling capillary electrophoresis-based separation techniques to ESI and MALDI-MS.

Coupling CE-based separation techniques to MS creates a powerful platform for analysis of a wide range of biomolecules from complex samples because it combines the high separation efficiency of CE and the sensitivity and selectivity of MS detection. ESI and MALDI, as the most common soft ionization techniques employed for CE and MS coupling, offer distinct advantages for biomolecular characterization. This review is focused primarily on technological advances in combining CE and chip-based CE with ESI and MALDI-MS detection in the past five years. Selected applications in the analyses of metabolites, peptides, and proteins with recently developed CE-MS platforms are also highlighted.

Liquid chromatography-matrix-assisted laser desorption/ionization mass spectrometric imaging with sprayed matrix for improved sensitivity, reproducibility and quantitation.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging (MSI) has been employed as a detection method for both capillary electrophoresis (CE)-MALDI and liquid chromatography (LC)-MALDI analyses. Based on our previous studies, here we report a new interface to couple LC with MSI by employing an automated matrix sprayer. The LC trace is directly collected on a ground stainless steel MALDI plate and dried. The matrix is sprayed on the MALDI plate using a programmable matrix sprayer. With the highly uniform matrix layers produced from the sprayer, the MS image signal quality is significantly improved with enhanced signal-to-noise ratios for analyte peaks. With the programmable matrix application and imaging MS data acquisition, the new LC-MSI platform exhibits highly stable and reproducible performance. A total of 87 bovine serum albumin (BSA) tryptic peptides and 295 putative neuropeptides from blue crab pericardial organs have been observed with LC-MSI analysis, exhibiting better performance in terms of peptide coverage than regular LC-MALDI with discrete spot collection and our previously reported LC-MSI interface with the matrix being delivered by a capillary. In addition to relative quantitation with isotopic labeling as we have previously demonstrated, we performed the first absolute quantitation using the new LC-MSI platform and obtained accurate quantitation results for neuropeptides, indicating great potential for quantitative analysis of complex samples.

Development of a fast radiation detector based on barium fluoride scintillation crystal.

Barium fluoride (BaF2) is an inorganic scintillation material used for the detection of X∕gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF2 has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF2 has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF2 scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands.

Semi-automated liquid chromatography-mass spectrometric imaging platform for enhanced detection and improved data analysis of complex peptides.

A semi-automated analytical platform featuring the coupling of monolithic reversed-phase liquid chromatography (RPLC) to matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI MSI) has been developed and evaluated. This is the first time that LC separation is readily coupled to MS imaging detection for the analysis of complex peptide mixtures both qualitatively and quantitatively. Methacrylate-based monolithic column with C12 functional groups is fabricated for fast RPLC separation. The LC flow and matrix flow are collected on a commercially available MALDI plate which is mechanically controlled and analyzed with MALDI MSI subsequently. Both tryptic peptides digested from bovine serum albumin (BSA) and endogenous neuropeptides extracted from the blue crab Callinectes sapidus are analyzed with this novel LC-MSI platform. Compared with regular offline LC fractionation coupled with MALDI MS detection, LC-MSI exhibits significantly increased MS signal intensity due to retaining of temporal resolution from separation dimension via continuous sampling, which results in increased number of peptides detected and accurate quantitation. In addition, imaging signals enable improved data analysis based on either mass-to-charge ratio or retention time, which is extremely beneficial for the analysis of complex analytes. These findings have demonstrated the potential of employing LC-MSI platform for enhanced proteomics and peptidomics studies.